Embossed leather and process for preparing the same



' an- 17,1967 H. FUCHS 3,298,851

EMBOSSED LEATHER AND PROCESS FOR PREPARING THE SAME Filed Nov 'o'o, 1964INVENTOR HER/MANN FUCHS BY I I 3 M9 w q' rOR 5 United States Patent3,298,851 EMBOSSED LEATHER AND PROCESS FOR PREPARING THE SAME HermannFuchs, Weinheim an der Bergstrasse, Germany,

assignor to Carl Freudenherg, Weinheim an der Bergstrasse, Germany, acorporation of Germany Filed Nov. 30, 1964, Ser. No. 414,813 Claimspriority, application Germany, Dec. 5, 1963, F 1,475 17 Claims. (Cl.l1711) The present invention relates to embossed leather and a processfor preparing the same, and more particularly to leather having anenduring pattern embossed on the surface without burning or scorching ofsuch surface, and to a process for imparting at elevated temperaturessuch enduring pattern to the leather,.which isin particular pretreatmentcondition.

It is known to produce various decorations and designs on leather bysearing techniques or branding techniques. This is especially true inthe case of burning identifying initials or symbols into leathersaddles, and the like, by the use of red hot irons. Actually, thebranding with red hot irons is more amatter of identification thandecoration of leather articles, as the searing of the leather isactually not intended for the purpose of embellishing the surface of theleather inasmuch as such surface is merely charred by this brutaltreatment. Besides detracting from the ornamental aspects of the leatherarticle and from the beauty of the leather itself, a significantamountof searing or burning in effect greatly impairs the strengthcharacteristics of the leather. Leather hides which have been subjectedto such searing or burning techniques cannot be used for shoe uppers asthe permeability thereof to water vapor and air is too great. Moreover,the penetrating odor which clings to seared leather for months and evenyears, is also a great disadvantage. For this reason, the decoration ofleather with so-called burning styli, which can be operated manually orby machine, has not acquired any great popularity in the leatherindustry.

Therefore, other more practical processes have been utilized fordecorating leather. Bark-tanned skivers have been pressed betweenengraved plates having a temperature of about 50 C. in order to causethe pattern from such plates to be impressed upon the surface of theleather. Designs impressed in this manner, however, are not particularlylong lasting. When leather treated in this way is folded or rubbed, thesurface again becomes smooth. In the language of the trade, the designirons itself out. Furthermore, this impressing of designs at 50 C. islimited to bark-tanned leather (see H. Gnamm, Fachbuch fiir dieLederindustrie, 1958, 5th Ed., p. 488). For this reason, a shoe upperleather loses its decorative design rather rapidly when impressedbetween engraved plates in the foregoing manner. Significantly, sincechrome tanning is predominant today in the leather industry, and sincethe aforesaid impressing technique is limited to bark tanned leathers,such process is of limited worth, as it cannot be utilized on most ofthe leathers being currently produced.

It should be noted that leather that is initially soft is only hardenedupon being subjected to a pressing process as might be used to impartdesigns to the leather surface. By way of the teaching in German PatentNo. 673,234, such disadvantage is said to be eliminated by firstproviding napa leather, i.e. suede leather, with a grain pressing of anysuitable kind, then disposing the leather upon a soft underlayment whichpermits the leather to move freely on all sides, and finally ironing theleather from the back side with a very hot plate which is made to slideover the leather surface without great pressure.

This ironing is not to be confused with other prior art hot ironingknown by such name and which is done for the purpose of producing abright or smooth surface on the leather. Such other prior art ironing iscarried out such that the leather is prevented from shrinking due to itsbeing held fast on all sides by the firm pressing contact therewith ofthe ironing plate, such other prior art hot ironing avoiding the use ofhigh temperatures as well, so as not to damage the leather. The same istrue with respect to hot pressing, in which the leather is alsorestricted in its expansion by reason of the use of male and female diesfor holding the leather. If desired, the ironing in accordance with theteaching of German Patent No. 673,234, wherein the leather is free tomove, can be performed repeatedly, and the same is performed gently soas not to work out the embossed pattern pressed into the leather. Thehot treatment of the freely movable leather will cause the previouslyimpressed embossed pattern to draw together, and the leather thusundergoes a puckering, which brings about the drawing together of thenapa or suede leather in the manner of an embossed pattern, mainly, butalso to some extent in the'manner of a natural graining. The leather isfixed in this condition. The hot ironing can be continued until thedesired effect is achieved, but, ofcourse, the leather must not beoverheated or it will become stiff and brittle (see German Patent No.673,234).

In practice, however, it appears that the more lastingly the pattern isimprinted, the stiffer and harder the leather unfortunately becomes.

French Patent No. 1,130,538 discloses a process for the treatment ofleather which eliminates the use of presses and other costly machines bylaying an asbestos plate having openings therein upon the leather andthen playing an open flame over the surface thereof and directly againstthe leather portions exposed through the asbestos plate openings.However, this process has the same disadvantages as that using a stylusfor burning designs into a leather surface, namely bad odor andbrittleness, reduced tearing strength, etc.

In US. Patent No. 1,744,553, an alternate technique is set forthcontemplating the piercing of leather with sharp punches to about /1 ofthe leather thickness, such that a design imparted in this manner cannotbe ironed out, and such that the leather remains waterproof to someextent inasmuch as the leather is not perforated all the Way through bythe punching step. Nevertheless, among the disadvantages of thistechnique is the fact that fibers of leather will project into thepartial perforations and present an unsightly appearance. Such stubbornbristles or fibers can only be removed by using heated punchesmaintained at a temperature at which the leather fibers will sear butnot burn, i.e., approximately 250 C. Such process is difficult toperform because of the normal problems which arise with natural leather.Specifically, although a machine may be adjusted to punch holes ordepressions of of a mm. in depth in a leather having a thickness of 1mm., whereby such leather will be pierced only 4 through, it is wellknown that the thickness of a raw hide or pelt, and hence of the leathermade therefrom by tanning, is anything but uniform. Many points are only0.5 mm. in thickness, for example, while others are more than 0.7 mm. inthickness. Consequently, the punching needles in some places pierce allthe way through the leather, and in others, i.e. the thicker portions,the leather is only scratched and not really pierced significantly atall. The pattern, which is actually nothing more than a hole pattern, istherefore neither ornamental nor attractive in accordance withcurrent-day fashion standards.

Accordingly, up to the present there has been no process by means ofwhich a decoration of leather can be carried out mechanically, e.g.using an embossing machine, which is economical yet withoutdisadvantages of some kind.

It is an object of the present invention to overcome the foregoingdrawbacks and to provide a leather having an enduring pattern embossedon the surface thereof With out burning and scorching of such surface,and to provide a. process for imparting such enduring pattern into theleather wherein the leather is in a particular pretreatment condition.

It is another object of the present invention to provide a process ofthe foregoing type in which the leather is heated at elevatedtemperatures, yet the design of the embossing tool at the temperatureused is only impressed in the surface of the leather but in a permanentmanner.

It is a further object of the present invention to provide such aleather which is chrome-tanned grain leather, such as aniline-dyed topgrain leather.

Other and further objects of the present invention will become apparentfrom a study of the within specification and accompanying drawing inwhich:

FIG. 1 is a perspective view of an apparatus for imparting an enduringpattern into the surface of leather by means of a manually operatedheated roller, in the manner of the present invention, and

FIG. 2 is a more or less automatically operated apparatus for impartingan enduring pattern into the surface of leather in the manner of theinvention.

It has been found in accordance with the present invention that leatherhaving an enduring pattern embossed on the surface thereof withoutburning and scorching of such surface may be made by the process whichcomprises hot impressing a pattern onto a paratfin or wax coated surfaceof the leather at a temperature between about 200-650 C. The leathersurface is preferably hot impressed in smooth, fiat condition, free fromWrinkles and folds. The leather may be aniline-dyed top grain leatherwhich has been chrome-tanned. Preferably, the leather is treated whiledisposed on an elastic underlayment, and

the hot impressing may be carried out by passing an engraved rollerheated to the required temperature into pressing contact with theparaffin coated surface. Advantageously, the leather surface, before theparaffin or wax coating is provided thereon, is treated with a leatherdressing that gathers mostly in the strata of the leather close to thesurface yet below such surface, whereby to prevent the after-appliedparaffin or wax from penetrating substantially into the leather. Suchdressing may be in the form of an albuminoid substance.

It will be appreciated by the artisan that decoration by searing orburning is actually possible without damage to grain leathers so long ascertain minimum requirements are observed. Firstly, the leather to bedecorated should be made by chrome tanning as leathers tanned withnatural materials shrink by up to 20% and more in the searing decorationcarried out in accordance with the present invention. Ideally, theshrinkage should amount to although this is practically impossible toachieve under normal conditions. Where some shrinking of the leather isnot detrimental to the purpose for which the same is to be used, thennatural tanned leathers may be employed. Secondly, the leather, such aschrometanned leather, is not to be burned or seared in unprotectedcondition, but instead such leather must be hotembossed in a particularpretreatment condition, i.e., it must first be sprayed with an aqueousemulsion of parafiin or wax, and the excess paraflin or wax must beremoved.

The paraffin or wax emulsion is made in the conventional manner bystirring ordinary parafiins or waxes having a melting point betweenabout 5070 C. in water with an emulsifier being present as well. A thincoating of parafiin or wax thus forms on the surface of the chromeleather, which serves to protect the protein material of the leatherbeneath such coating from burning.

Still better results are achieved if a leather dressing is used beforethe application of the protective layer of paraffin or wax, as notedabove, with such leather dressing preferably not penetrating too deeplyinto the leather. It will be realized that the parafiin or wax coatingitself does not long remain on the surface of the leather and either thehot impressing step must take place soon after such coating has beenadded or the prior treatment with the leather dressing of albuminoidsubstance must be carried out and then the paraffin or wax coatingadded.

In accordance with the present invention, all paraffins and waxes havinga melting point substantially between about 50-70 C. may be used for thedesired coating, such as parafiin fractions having a melting point rangebetween about 5065 C., tetracosane (M.P. 51 C.), pentacosane (M.P. 54C.), beeswax (MP. 60.562 C.), tricon tane (MP. 66 C.), hentricontane(MP. 69 C.), and the like. If the melting point of the paraffin or waxis substantially below 50 C., then the paraffin or wax soaks too deeplyinto the leather surface, whereas if such melting point is substantiallyabove 70 C., the paraffin or wax is difficult to emulsify.

As emulsifiers which may be used in accordance with the presentinvention, the following commercially obtainable products areparticularly useful:

Emulgator PW, Chemische Werke Hiils of Germany.

Emulgator FOX, Chemische Werke Hills of Germany,

Emulgator GFW, Chemische Werke Hills of Germany.

Emulgin 365, Deutsche Hydrierwerke, Dusseldorf, Germany.

Emulgin 535, Deutsche Hydrierwerke, Dusseldorf, Germany.

Ethomid HT/ 15, Armour 2 Company GmbH, Hamburg,

Germany.

Emulsogen P, Anorgana Gendorf of Germany.

Emulsifier, P.W. Bohme Fettchemie of Germany.

The concentration of the paraffin or wax emulsions used in accordancewith the present invention should be substantially between about 5l5%,and preferably 10%, by weight, with the remainder being water. If theconcentration of the emulsion is below about 5%, then such smallquantities of parafiin or wax are deposited on the leather that thedesired effect can no longer take place. Where the concentration of theemulsion is above 15%, the leather takes on a waxy or fatty characterand the appearance of the ultimate embossed leather is unattractive. Inparticular, it has been found that a ratio of parafiin orwaxzwaterzemulsifier of 10:88.15 :1.2 is particularly useful inaccordance with the present invention. On the other hand, as between theemulsifier and the paraffin or wax, generally the emulsifi-erzparaffi-nor wax ratio may be 0.53:10 or 0.05-0.3z1 in parts by weight. It is notadvisable to use a higher ratio of emulsifier to paraflin or wax thanthat indicated, as an excessive amount of emulsifier is not necessaryand too high a concentration of emulsifier may be even detrimentalinasmuch as it would represent a proportional decrease in the quantityof paraffin or wax necessary for the intended purpose.

Whereas the aqueous dispersion of the albuminoid, preferablynon-thermoplastic substance, may be effectively applied in an amountsubstantially between 330 grams per square meter and preferably between3-7 grams per square meter, the aqueous emulsion of the paraffin or waxis generally applied in an amount substantially between about 2-20 gramsper square meter and preferably between about 2-5 grams per squaremeter. Lower amounts of the emulsion should not be used since thesingeing and burning away of leather fibers cannot be prevented duringthe embossing under such conditions, whereas if a greater amount thanthat specified in the range is used, the leather will take on a fattyappearance and the finished product will have an ob jectionable surfaceappearance and feel.

As aforesaid, such dressing must work into the strata of the leatherclose to the surface in order to prevent the paraflin or wax frompenetrating much beyond the leather surface, although, on the otherhand, the dressing must not itself remain on the surface or this maydetract from the value of the paraffin or wax coating. More importantly,a dressing that penetrates too little and thus remains on the surface ofthe leather produces an unnatural cold feel in the leather. Theappearance of the leather then would be more like that of oilcloth. Themost unpleasant characteristic, perhaps, is that the dressing, ifinsufi'iciently adapted to the leather, can be peeled away or the samemay crack or flake off by itself. g g

It will be appreciated in accordance with the present invention that theparaffin or Wax coating added to the leather prior to embossing protectsthe surface from too strong a scorching during the hot embossing, as theleather would break and crack if embossed ,wit-hout the paraffin' or waxpretreatment, and would thus beunsuitable for various purposes, such asleather shoe uppers, and the like. Moreover, the raised portions of thehot-impressed'design in the leather would alsobreak and crack. In thesame way, the albuminoid dressing which is applied to the leather aftertanning and dyeing but before the paraffin or wax coating, serves toretain the paraflin or Wax at or near the surface of the leather,whereas without prior albuminoid substance treatment of the leather, theparafiin or wax applied thereto would immediately diffuse into theleather and would not remain sufliciently at the outer surface of suchleather for the intended purpose.

There may be used in accordance with the present invention, therefore,as dressing or finishing substances which gather for the most part inthe strata of the leather close to the surface yet below such surface,in order to prevent after-applied paraffin or wax from penetratingsubstantially into the leather, various albuminoid substances includingalbumin, such as egg albumin, blood albumin, and casein, for examplefrom milk, typicallyin the form of acid casein. These substances swellin cold water and is between egg albumin and blood albumin, the formeris used for light color leather dressing and the latter is used for darkcolor leather dressing. Generally, these albuminous substances may beused in 0.5-2%, preferably 1%, aqueous dispersions, and egg albumin,blood albumin and casein may be used alone or in admixture with oneanother.

In particular, an albuminoid non-thermoplastic dressing agent forleather manufactured under the name Luron Binder by BASF A.G.,Ludwigshafen, Germany, has been found to be quite suitable as thedressing substance in accordance with the invention. These agents whichact as binders and/ or softeners are albuminoid condensation products incolloidal aqueous dispersion slightly alkaline in nature. The pH of atenfold diluted aqueous dispersion is about 8.

Generally, the aqueous dispersion of the albuminoid substance may beapplied in an amount substantially between about 3-30 g./m. to theleather, whereas the paraflin emulsion may be applied in an amountsubstantially between about 2-20 g./rn. to the leather.

Actually, the searing or burning must be carried out with a heavy,engraved steel roller which is heated to 200-650 C., preferably 250-400C., and especially about 350 C., and rolled over the leather just onceat a given speed, such as about 7.5 meters per minute, the leatherpreferably, in turn, being situated upon an elastic underlayment asnoted above. Although the line pressure of the roller may be generally5-10 kilopounds per centimeter, especially 7 kp./cm., there is actuallyno compacting of the leather being embossed, and thus no effectivedamage in the thickness or cross-section of the leather.

As used herein, i.e., in the specification and claims,

the term parafiin means both paraflins and waxes which have a meltingpoint substantially between about 50-70 C., and especially thosesubstances whose melting points have been specifically enumeratedhereinabove.

Referring to the drawing, FIG. 1 shows the simplest embodiment of themaking of leather with an enduring pattern embossed on the surfacethereof, without burning and scorching, using a manual arrangement. Theroller 1 is connected with a framework 2 which can be moved by theoperator so that the roller is displaced back and forth over the leather3 disposed on a flat surface, table, or the like. The framework 2 isprovided with a tray for receiving weights of various amounts, dependingupon the type of leather, the degree of embossing, etc. The roller 1 maybe heated to ZOO-600 C., or even up to 650 C., and then rolled once overthe piece of leather 3 lying on the table. Generally, since the weightof the roller itself is not sufficient in order to transfer the patternto the leather, the additional pressure required is arrived at by addingone or more weights to the tray of the framework 2. The actual weight tobe used can be determined only by trial and error experiments within thepurview of the artisan, since different patterns of courserequiredifierent pressures, and the artisan will select a particularweight depending upon the degree of embossing desired, i.e.slight,moderate, or vivid. In this regard, if the roller has only a fewelevated points which are used to press the desired pattern into theleather surface, only' a slight pressure will be required. On the otherhand, where there are many elevated points, the pressure with whichthese elevated points are pressed into the'leather'will becorrespondingly greater. Accordingly, additional weights must be addedto the tray of the framework 2. A line pressure of substantially betweenabout 5-10 kilopounds/cm. may be used generally in this connection, andpreferably 7 kilopounds/cm., with a speed of relative movement betweenthe leather and the pattern, embossing roller of substantially about 7.5meters/minute.

In FIG. 2, a preferred more or less automatic arrangement is shown inwhich a roller 4, which has been brought to the desired temperature byelectrical heating or other heating method, is situated stationarilyupon an underlayment 9, such that the axis of the roller is at aconstant position with respect to the underlayment. Nevertheless, theroller 4 is able to rotate about its axis and this is accomplished asthe leather 6 is drawn under the roller in the direction of the arrow inthe manner shown. In order that the leather will be always stretchedsmooth beneath the roller, a friction bar or slide bar 7 is situated infront of the roller such that the leather 6 is pulled over bar 7 so asto raise the same from the underlayment 9 and then the leather passesunder the rotating roller 4. It will be appreciated that if the rod 7 isomitted, it is possible that wrinkles in the leather 6 will not smooththemselves out before reaching the roller 4. A wrinkle or crease of thissort in the leather, since it is substantially thicker than the rest ofthe leather, will be exposed to much stronger pressure, whilepractically no pressure will be brought to bear on the portions adjacentthereto. As a result, due to the excessively great pressure, the leatherat the creases will become brittle, and also will be over-burned, whileno pattern at all will be transferred at the other areas of the leatheradjacent thereto.

In the embodiment of FIG. 2, the Weight of the roller 4 may be providedso great that the required pressure will be produced under all operatingconditions. In many cases, however, the pressure may even be too great.To reduce the weight and accordingly the pressure of the roller on theleather, relieving disc rollers 8 may be provided. By their being pushedtogether and against the shaft 5 of roller 4, the disc rollers 8 causethe weight of the roller 4 on the leather piece 6 to be relieved in thedesired way. Nevertheless, as in the case of the embodiment of FIG. 1, aline pressure of substantially between about 5-10 kilopounds/ cm. may beused generally in this connection, and preferably 7 kilopounds/cm., witha speed of relative movement between the leather and the patternembossing roller of substantially about 7.5 meters/ minute.

As the artisan will appreciate, it is also possible to carry out theimpressing in accordance with the previously described procedure suchthat the leather is maintained in a constant or fixed position withrespect to the underlayment 9, while the roller 4 is rolled over thepiece of leather 6 lying on the table or other support.

Significantly, the leather 6 does not rest upon an iron or Woodenplaten, but rather an elastic underlayrnent, such as one made from foamrubber or a platen which is covered with leather. Tests have shown thatwhere such elastic underlayment is present, the pattern burned into theleather is longer lasting and better looking than otherwise.

The process of the present invention is applicable to all types ofleathers, such as calf skin, cowhide, sheepskin and pigskin, withconsistently good results. Such leathers may be treated by conventionalchrome-tanning, aftertanning and dyeing techniques [see Handbuch derGerbereichemie und Lede-rfabrikation, W. Grossmann, publisher Springer,Vienna, 1955, p. 373,,Band 3: Das Leder, Teil 2: Die Lederarten undderen Herstellung (Manual of Tanning Chemistry and Leather Manufacture,vol. 3: The Leather, Part 2: Types of Leather and Their Production)prior to dressing, parafiin or wax coating, and embossing, in accordancewith the invention.

The period of time during which the leather must be in contact with theelevated points on the engraved or embossed roller is actually on theorder of about 1 second duration. If the leather is pulled through toofast, the desired pattern may not be impressed plainly enough, Whereasif the time of contact is too long, damage may be done to the leather.As the artisan will appreciate, the time of hot impressing the patterninto the parafiin coated leather surface depends upon the temperature,the type of leather, and the type of embossing design utilized, but aspeed of relative movement between the leather and roller of 7.5 m./min.is generally sufficient.

Advantageously, the process of the invention may be carried out withaniline-tanned grain leather, since where aniline-tanned grain leatheris singed, no destruction of the dye takes place and, therefore, thistype of tanned leather is compatible with the hot impressing techniquesof the present invention using the paraffin protected coating.Nevertheless, as the artisan will appreciate, many dyes are changed as aresult of heat, but this does not necessarily detract from thedecorative effect desired, and such leathers Which have been treatedwith heat changeable dyes may also be hot impressed in accordance withthe present invention whereby the changes which take place will add tothe decorative effect.

The following examples are set forth by way of illustration and notlimitation.

Example 1 Calfskin (butt) leather (average thickness 1.7 mm.) which hasbeen chrome-tanned and thereafter treated by mineral resin syntheticafter-tanning, and aniline-dyed, in the conventional manner, is preparedfor embossing by applying to the grain side 7 g./m. of a 1% aqueousslightly alkaline colloidal dispersion of a non-thermoplastic albuminoidcondensation product (i.e., Luron Binder, BASF A.G., Germany) and then 5g./m. of an 11.3% aqueous emulsion of a paraflin fraction (M.P. 60 C.)and an emulsifier (Emulgator PW, Chemische Werke Hills, Germany),wherein the ratio of paraflinzwaterzemulsifier is :88.15: 1.2. Theso-treated leather is then embossed with a roller having an embossingpattern With 0.8 mm. elevations, and heated to 350 C., in accordancewith the arrangement depicted in FIG. 1. The roller is drawn over theleather at a speed of 7.5 meters/min. (0.125 m./sec.), using a linepressure of about 7 kilopounds/cm. The hot embossed parafiin coatedleather obtained in accordance with the foregoing possesses permanentdesigns impressed therein by the embossing which cannot be ironed out,yet which do not represent seared or burned designs in the leather aswas the case in the past. Instead, due to the presence of the paraffincoating, the heat of the embossing roller is dissipated in the parafiinor wax sufiiciently to prevent scorching or burning. of the leathergrain, yet the heat at the pressure used is sufiicient to impart apermanent and attractive design in the leather. Such leather is freefrom a scorched or burned odor.

Example 2 Calfskin (neck) leather (average thickness 1.3 mm.) which hasbeen chrome-tanned and thereafter treated by vegetable after-tanning,and aniline-dyed, in the conventional manner, is prepared for embossingby applying to the grain side 3 g./m. of a 1% aqueous slightly alkalinecolloidal dispersion of a non-thermoplastic albuminoid condensationproduct of the same type as used in Example 1, and then by applying 2g./m. of an 11.3% aqueous emulsion of beeswax (solidification point60.56 2 C.) and an emulsifier (Emulgin 365, Deutsche Hydrierwerke,Germany), wherein the ratio of wax:water:emulsifier is 10:88.15:1.2. Theso-treated leather is then embossed with a roller of the type used inExample 1, which is heated in this case to 300 C. The roller is drawnover the leather under the same conditions as those set forth in Example1, using a line pressure of about 7 kilopounds/cm., and similar resultsare obtained.

Example 3 The procedure of Example 1 is repeated, using 20 g./m. ofemulsion rather than 5 g./m. as in Example 1, the emulsifier in thisinstance being that produced by P.W. Bohme Fettchemie, Germany, andsimilar results are obtained to those obtained in Example 1.

Example 4 Example 1 is repeated except that said embossing is done witha roller according to the arrangement depicted in FIG. 2, wherein theleather is pulled along under the roller at a linear speed of 7.5m./minute, using a line pressure of about 7 kilopounds/cm. Similarresults are obtained in this case to those obtained in Example 1.

Example 5 The procedure of Example 2 is repeated, except that theembossing is done with a roller according to the arrangement depicted inFIG. 2, wherein the leather is pulled along under the roller at a linearspeed of 7.5 rn./rninute, using a line pressure of about 7 kilopounds/cm., and similar results to those of Example 2 are obtained.

Example 6 The procedure of Example 1 is'repeated, using in turntetracosane, pentacosane, tricontane and hentricontane as the paraffincomponent of the emulsion with calfskin, cowhide, sheepskin and pigskin,respectively, and similar results are obtained in each instance to thoseof Example 1.

In each of the foregoing examples, the excess aqueous emulsion isremoved prior to contact with the roller by wiping lightly the leathersurface, for example with a cloth or Wiping blade, suflicient emulsionbeing deposited in the leather surface portion to provide the desiredprotective parafiin coating for the hot embossing step.

It will be realized by the artisan that the foregoing specification andexamples have been set forth by way of illustration and not limitation,and that various modifications and changes may be made without departingfrom the spirit and scope of the present invention, which is to belimited only by the scope of the appended claims.

What is claimed is:

1. Process for imparting an enduring pattern into the surface of leatherwhich comprises hot impressing by line pressure contact a pattern onto aparafiin coated leather surface at a temperature between about 200- 650C., the parafiin of said paraffin coated leather surface having amelting point between about 50-70 C. and

being substantially present on the surface of the leather during the hotimpressing.

2. Process according to claim 1 wherein the leather surface is hotimpressed in smooth, flat conditions free from wrinkles and folds.

3. Process according to claim 1 wherein the leather is aniline-dyed topgrain leather.

4. Process according to claim 1 wherein the leather is chrome-tannedgrain leather.

5. Process according to claim 1 wherein the hot in pressing is carriedout by passing an engraved roller heated to a temperature between about200650 C. into pressing contact under a pattern embossing line pressureof substantially between about 5-10 ki-lopounds/cm. with said parafiincoated surface.

6. Process according to claim 5 wherein the leather being treated isprovided with an elastic under layment.

7. Process according to claim 5 wherein the leather surface, before theparaflin coating is provided thereon, is treated with a leather dressingthat gathers mostly in the strata of the leather close to the surfaceyet below such surface to prevent the after-applied paraffin frompenetrating substantially into the leather.

8. Process for imparting an enduring pattern into the surface of leatherwhich comprises hot impressing a pattern onto a paraffin coated leathersurface at a temperature between about 200650 C., the paraffin of saidparaffin coated leather surface having a melting point substantiallybetween about 5070 C. and being applied as an aqueous emulsion, saidleather surface before the paraffin coating is provided thereon beingtreated with a leather dressing composed of an aqueous dispersion of analbuminoid substance that gathers mostly in the strata of the leatherclose to the surface yet below such surface to prevent the after-appliedparaflin from penetrating substantially into the leather.

9. Process for imparting an enduring pattern into the surface of leatherwhich comprises hot impressing a pattern onto a paraffin coated,chrome-tanned, aniline-dyed top grain leather surface by passing anengraved roller heated to a temperature between about 200650 C. onceover the paraffin coated leather surface in pressing contact therewithunder a pattern embossing line pressure of substantially between about5-10 kilopounds/cm. while the leather is maintained in contact with anelastic under layment in smooth, flat condition free from wrinkles andfolds, the parafiin of said paraflin coated leather surface having amelting point substantially between about 50- 70" C. and being presenton the surface of the leather during the hot impressing.

10. Process according to claim 9 wherein the roller is in contact withthe particular portion of the surface being impressed for substantiallyonly about 1 second.

11. Process for imparting an enduring pattern into the surface ofleather which comprises hot impressing a pattern onto a parafiin coated,chrome-tanned, anilinedyed top grain leather surface by passing anengraved roller heated to a temperature between about 200- 650.

C. once over the paraffin coated leather surface in pressing contacttherewith so that such roller is in contact with the particular portionof the surface being impressed for'substantially only about 1 secondwhile the leather is maintained in contact with an elastic under laymentin smooth, flat condition free from wrinkles and folds, the paraffin ofsaid parafiin coated leather surface having a melting pointsubstantially between about 50-70" C. and the leather surface, beforethe paraffin coating is provided thereon, being in the form of apretreated surface which has been pretreated with a leather dressingthat gathers mostly in the strata of the leather close to the surfaceyet below such surface to prevent the after-applied paraffin frompenetrating substantially into the leather.

12. Process according to claim 11 wherein said dressing is an aqueousdispersion of a non-thermoplastic albuminoid substance.

13. In the process for imparting an enduring pattern into the surface ofleather with a pattern embossing means, the improvement which comprisesapplying be tween about 3-30 gm./m. of an albuminoid leather dressingthat gathers mostly in the strata of the leather close to the surfaceyet below such surface to prevent after-applied paraffin frompenetrating substantially into the leather, then applying between about2-20 gm./m. of an aqueous emulsion of a paraffin having a melting pointsubstantially between about 50-70 C. with an emulsifier, in a ratio ofemulsified2paraffin of between about 0.5-3:10, in a concentration ofbetween about 5-15% in water, onto the surface of a chrome-tannedleather on which the pattern is to be imparted, removing excess paraffinto provide a thin paraffin coating on the leather surface which protectsthe protein material therebeneath from burning, and hot impressing apattern onto the parafiin coated surface at a temperature between about200650 C. for substantially about 1 second.

14. Improvement according to claim 13 wherein the leather isaniline-dyedtop grain leather, wherein the aqueous emulsion is in the ratio ofparaflinzwaterzemulsifier of about 10:-8=8.15:1.2, wherein a speed ofrelative movement between the leather and the pattern embossing means ofsubstantially about 7.5 meters per minute is used with a patternembossing line pressure of substantially between about 5-10kilopounds/cm., and wherein the leather surface, before the paraffincoating is provided thereon, is treated with a leather dressing in theform of an aqueous dispersion of an albuminoid non-thermoplasticsubstance.

15. Leather having an enduring pattern embossed on the surface thereofwithout burning and scorching of such surface which is made by theprocess which comprises hot impressing by line pressure contact apattern onto a paraffin coated surface of the leather at a temperaturebetween about 200650 C., the paraffin of said paraflin coated leathersurface having a melting point substantially between about 50-70 C. andbeing substantially present on the surface of the leather during the hotimpressing.

16. Leather having an enduring pattern embossed on the surface thereofwithout burning and scorching of such surface, which is made by theprocess which comprises hot impressing under a pattern embossing linepressure of substantially between about 5-10 kilopounds/cm. a patternonto a paraffin coated surface of a chrome-tanned, aniline-dye top grainleather, in which the parafiin of such paraffin coated surface has amelting point substantially between about 50-70 C. and is present on thesurface of the leather during the hot impressing at a temperaturebetween about 200650 C. while the leather is maintained in contact withan elastic underlayment in smooth, flat condition free from wrinkles andfolds.

17. Leather having an enduring pattern embossed on the surface thereofwithout burning and scorching of such surface, which is made by theprocess which comprises hot impressing under a pattern embossing linepressure of substantially between about 5-10 kilo- .pound/cm. a patternonto a paraffin coated surface of a chrome-tanned, aniline-dyed topgrain leather, in which the paraffin of such paraffin coated surface hasa melting point substantially between about 5070 C. and is present onthe surface of the leather during the hot impressing, at a temperaturebetween about 200650 C. while the leather is maintained in contact withan elastic underlayment in smooth, flat condition free from wrinkles andfolds, said surface of the leather prior to being parafiin coated havingbeen treated with a leather dressing of an albuminoid substance thatgathers mostly in the strata of the leather close to the surface yetbelow such 11 12 surface toprevent after-applied parafiin frompenetrating OTHER REFERENCES substantlany Into the leather Mudd: LeatherFinishes, 2nd Ed., 1955, A. Harvey Publisher, 1955, pp. 76, 78, 79, 115.1 References Clted by the Examiner Sharphouse: The LeatherworkersHandbook, Nov. UNITED STATES PATENTS 5 1963, Leather ProductsAssociation for England, Scotland 1,696,815 12/1928 Small 117-442 andWales, pp. 5, '136, 140, 141, 167, 168 and 169.

1,700,968 2/1929 Ballou et 2111. Wilson: Modern Practice in LeatherManufacture, 1,704,718 3/1929 Torrance 1 X 1941, Reinhold Pub. Corp, p.574. I

FOREIGN PATENTS ALFRED L. LEAVITT, Primary Examiner. 664,398 9/1938Germany.

401,414 11/1933 Great Britain. RALPH N

1. PROCESS FOR IMPARTING AN ENDURING PATTER INTO THE SURFACE OF LEATHERWHICH COMPRISES HOT IMPRESSING BY LINE PRESSURE CONTACTS A PATTERN ONTOA PARAFFIN COATED LEATHER SURFACE AT A TEMPERATURE BETWEEN ABOUT200*650*C., THE PARAFFIN OF SAID PARAFFIN COATED LEATHER SURFACE HAVINGA MELTING POINT BETWEEN ABOUT 50-70*C. AND BEING SUBSTANTIALLY PRESENTON THE SURFACE OF THE LEATHER DURING THE HOT IMPRESSING.